Select Filter For Your Digital Camera

effect of neutral density by Gary Turner

If you’re into digital photography and are skilled at using an image editor like Photoshop, you may feel that you no longer need lens filters because you can get similar or better results by digitally editing your images. However, many good reasons exist for considering using a few filters, including a protective filter to prevent damage to your lens in harsh environments. In this technique, you learn about four filters that you’re likely to find useful: the protective filter, neutral density filter, polarizing filter, and infrared filter.

STEP 1: DECIDE IF YOU SHOULD USE A PROTECTIVE FILTER (UV OR SKYLIGHT)
Protective filters are primarily designed to protect the front element of a camera lens from dust, moisture, scratches, and breakage. The two most common protective
filters are the UV-absorbing filter and skylight filters. There are two schools of thought on using protective” filters. Some feel strongly that you should always protect the lens on your digital camera or any camera) with a protective filter such as a UV or skylight filter. Others feel equally strong about not adding extra glass to a lens that could possibly degrade the quality of the image. If you take good care of your camera and you avoid using it when and where the lens could get damaged, you may not need a protective filter. If you use your camera in harsh environments where the lens could get damaged or where the lens frequently gets wet or dirty and needs to be cleaned often, you may want to buy and use a UV or skylight filter.

Important: Most of the damage done to camera lenses occurs when they are improperly cleaned. If you decide not to purchase and use a protective lens filter, use a soft clean cloth to clean the lens. Old cotton t-shirts make excellent cleaning cloths. If you clean your lens often, consider buying a lens cleaner kit that has a soft cloth plus a small bottle of cleaning liquid. Avoid “scrubbing” the lens because you can remove or scratch the coating on the lens.

STEP 2: CONSIDER WHEN YOU SHOULD USE A POLARIZER
One of the more valuable and tricky-to-use filters is the polarizer. You can use polarizers to reduce reflections and to make richer colors—sometimes. Admittedly, the successful use of a polarizer requires some knowledge and a bit of luck. Because a polarizer’s effect varies depending upon your camera’s angle to the sun, you have to have chosen a place to shoot where the camera’s orientation allows you to “polarize” the light—and you have to know how to adjust the polarizer.

Warning: Too much polarization can increase contrast and color saturation in a photograph so much that it can look unnatural and even posterized. Until you’ve gained some experience with a polarizer, shoot the same picture with varying amounts of polarization so that you end up with photo you like.

You can buy two types of polarizers: circular and linear. Your best choice is a circular polarizer because some digital cameras may not work with a linear polarizer. To view the effect of a polarizer, you must look on your camera’s LCD monitor because you won’t be able to see the change through an optical viewfinder. Be aware that your
camera may also compensate for the darker skies by increasing exposure, which causes clouds to lose valuable detail, so you will want to take a quick look at the histogram (if your camera has one) to make sure your exposure is correct. The strongest effect from a polarizer occurs when you shoot at a right angle to the sun. As you turn more toward or away from the sun you gain less benefit from the polarizer, and the polarizer
blocks less light to your camera’s image sensor. A polarizer can cut down on the amount of light to your camera’s image sensor ranging between one and two stops. Besides being able to control reflections, you can also use a polarizer to enhance or deepen the intensities of colors such as a blue sky, red and orange leaves, or green trees and plants.Notice the richer blue of the sky, and the colors in the red rocks. This is a good example of when a polarizer’s ffects should be used sparingly. Overdarkening the sky would have been easy to do in this situation, giving the scene an unnatural appearance. Another good use for a polarizer is to reduce or eliminate glare from reflective surfaces like water or
glass.

STEP 3: CONSIDER WHERE YOU MIGHT USE A NEUTRAL DENSITY FILTER
Neutral density filters are designed to reduce the amount of light that gets to the image sensor in your digital camera without affecting the color. Although this may seem contrary to the way you usually work, where more light helps you use a low ISO setting and a fast shutter speed for sharper pictures, you will soon find that neutral density filters can be some of the most useful filters you can buy. If you have ever seen a photo of a waterfall where the water looks like a silky stream of fog rolling down the rocks, then you’re likely to have seen the results of a photograph taken with a neutral density filter. Also, because of the mathematics behind the optics in compact digital cameras, achieving shallow depth-of-field in bright light is very hard. Using a neutral density filter, you can not only slow action down enough to get soft blurred water coming down a waterfall, but you can also improve the background blur behind your subject—a highly desirable feature for many photographers. Most neutral density filters are labeled in logarithmic
units, with each .3 equaling one stop of lightblocking ability. A filter labeled as .9 blocks three stops of light, and allows you to extend your exposure time by three stops. Some vendors label these same filters with a 2x (one stop), 4x (two stops), and 8x (three stops) filter factor notation. The effects are the same, only the labeling is different.

image by Gary Turner

Generally, when you use a neutral density filter, you also need to use a tripod because you will be shooting with slow shutter speeds. The longer your exposure time, the smoother the water flow and the longer the camera must be perfectly still. Experiment with shooting water, plants blowing in the wind, and different moving objects. Capturing subjects in motion with a neutral density filter can often yield exciting results. Get one and experiment with it—you’re more than likely to get results you would not be able
to get without one.

STEP 4: DECIDE IF YOU WANT TO USE AN INFRARED FILTER

image by * Minette

Some people like the effects seen in infrared photos but are discouraged by the difficulty of working with infrared film. If you ever were interested in infrared images, now is the time to buy an infrared filter! Used with the right digital camera, an infrared filter can
produce some outstanding photos, and infrared photos are easy to shoot digitally compared to shooting with infrared film in a film camera. Seeing the world bathed in infrared light, right on your LCD screen, can be pretty exciting. Trees and plants appear to glow, skies become jet-black, and skin often radiates with a strange glow.

STEP 5: PURCHASE FILTER ADAPTORS IF THEY ARE NEEDED
If you decide to purchase a filter, you may also need a filter adaptor. Filter adaptors allow you to attach a filter to a camera when they don’t have the same thread sizes.
For example, if your digital camera has 28mm threads and you want to use a filter that has 37mm threads, you can buy a step-up adaptor to attach the filter. Some of the most common thread sizes are 37mm and 52mm. If you have more than one digital camera, you can often use the same filters on cameras with different thread sizes by purchasing an adaptor. What do you do if your camera doesn’t have threads? Some digital cameras, such as the Nikon CoolPix 5700, do not have filter threads on the front of the lens. To be able to use third-party filters, you need to purchase a third-party filter adapter made for
“threadless” cameras, or you can try using gaffers tape or electrical tape—either will work.